A weighing type bale opener comprises a rack, a cotton charging conveying curtain, a brad nail curtain device, a cotton uniformizing beater, a cotton stripping beater and a quantitative cotton discharging mechanism. The cotton charging conveying curtain, the brad nail curtain device and the quantitative cotton discharging mechanism are arranged on the rack from front to back, the cotton uniformizing beater is located at the front side of the brad nail curtain device, and the cotton stripping beater is located at the back side of the brad nail curtain device and located over the quantitative cotton discharging mechanism; the brad nail curtain device comprises a first drive roll, a first driven roll and an annular belt, the annular belt is tensioned by the first drive roll and the first driven roll, wall plates are arranged at the left side and the right side of the annular belt respectively, multiple wood strips are arranged on the inner surface of the annular belt, each wood strip is provided with multiple brad nails, all the brad nails penetrate through the annular belt, and the tips of the brad nails are located at the outer side of the annular belt; the two wall plates are each provided with a sealing device capable of sealing a gap formed between the corresponding wall plate and the annular belt. According to the weighing type bale opener, fiber raw materials on the brad nail curtain device can be completely stripped out by the cotton stripping beater, and normal running of the brad nail curtain device and the weighing type bale opener can be guaranteed.